Pennsylvania

Pennsylvania's housing needs vary widely from Philadelphia to rural communities, and accessory dwelling units offer a flexible solution across that range. Philadelphia and Pittsburgh have adopted ADU ordinances, and interest is growing statewide. ADU Pass helps Pennsylvania homeowners navigate the permit process.

2,398 ZIP codes
68 Counties
1,611 Cities

State ADU details

State ADU law

Pennsylvania has NOT enacted a statewide ADU preemption law. Under the Pennsylvania Municipalities Planning Code (Act 247 of 1968, 53 P.S. §§10101 et seq.), local governments retain broad authority over zoning, including ADU permission, setbacks, parking, size limits, and owner-occupancy. ADU rules vary widely by township, borough, city, and county. One active bill in the 2025-2026 session, HB 2186 (chief sponsor Rep. John Inglis), would amend Title 53 of the Consolidated Statutes to provide for ADUs, but was laid on the table on 2026-04-13 after a Housing and Community Development Committee vote (reported as 19 yes, 7 no during committee action) and has not advanced to third consideration.

State financing programs

Pennsylvania does not operate an ADU-specific statewide loan, grant, or forgivable-loan program. The Pennsylvania Housing Finance Agency (PHFA) administers general first-time-homebuyer, down-payment-assistance, and purchase-plus-improvement programs that can apply to properties with ADUs when eligibility criteria are met, but none target ADU construction as a distinct product. Notably, PHFA's HFA Preferred conventional product explicitly excludes two-unit properties, which can complicate financing an owner-occupied primary home that has (or plans to add) an attached ADU depending on how the appraiser and investor classify the unit.

State insurance regimes

Pennsylvania operates the Pennsylvania FAIR Plan, a state-mandated insurer-of-last-resort association created by Act 233 of 1968 (Pennsylvania FAIR Plan Act, 40 P.S. §§1600.101 et seq.). The FAIR Plan writes basic property coverage for homeowners and small businesses who cannot obtain coverage in the voluntary market. Coverage is narrower than standard homeowners — typically fire, lightning, and basic named-perils dwelling coverage — and does not include comprehensive HO-3-equivalent protection. Pennsylvania is not in the federally backstopped Gulf/Atlantic wind-pool system (unlike North Carolina Coastal, Louisiana Citizens, or Texas Windstorm) and is not a declared WUI state. ADU coverage in Pennsylvania follows each admitted-market insurer's standard treatment of accessory structures (typically bundled under Coverage B 'Other Structures' at roughly 10% of dwelling coverage, or requiring a dwelling-fire or landlord rider when rented to a non-family tenant). No ADU-specific state insurance mandate, rider requirement, or premium-capping statute is in force.

State housing programs

Pennsylvania does not run a state-level pre-approved-ADU-plan catalog, statewide impact-fee-waiver statute for ADUs, or streamlined-review mandate. State-level programs that touch ADU-adjacent policy are primarily coordinated through the Department of Community and Economic Development (DCED) and PHFA, and act by funding or assisting local jurisdictions rather than by preemption. Local ADU momentum — Pittsburgh's by-right ADU ordinance in designated zones and Philadelphia's 2020 zoning-code ADU provisions — is authorized under municipal authority granted by the Municipalities Planning Code (Act 247 of 1968), not by state mandate.

  • Keystone Communities Program — DCED program that provides planning, design, and construction funding to municipalities for downtown revitalization, elm-street neighborhood improvement, facade grants, and blight remediation. Not ADU-specific. Participating municipalities can direct Keystone Communities funds toward housing-rehab and missing-middle projects where local policy supports ADUs.
  • Pennsylvania Land Use Planning Assistance (PALUPA) / DCED Land Use Planning Technical Assistance — DCED and associated local-government-services staff provide model-ordinance drafting, zoning-code review, and planning technical assistance to municipalities interested in modernizing zoning (including ADU permission). Acts through local adoption rather than state preemption.
  • Pennsylvania Municipalities Planning Code (Act 247 of 1968) Model-Ordinance Guidance — The DCED-published Pennsylvania Municipalities Planning Code PDF and companion Planning Series documents include model language municipalities can adopt, including for accessory uses, home occupations, and mixed-use areas. Not a statewide ADU mandate; a guidance and boilerplate library that municipalities may or may not adopt.

Known state issues (2)

  • legislative-session (since 2026-04-13) — ADU law in Pennsylvania remains wholly local through at least the end of the 2025-2026 session. Homeowners and practitioners should not assume any statewide preemption, minimum-size floor, or ministerial-review mandate will be in force during the current session. If HB 2186 is taken from the table and passes, the city and county profiles in this research will need immediate re-verification. (source)
  • policy-review (since 2026-04-20) — City-level ADU research for Pittsburgh and Philadelphia has a shorter freshness window than the state tier. Expect annual-to-biennial amendments to local codes even while state law holds constant. (source)
Federal (United States) — ADU-relevant rules and programs

Federal ADU law

The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.

Federal financing programs

Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.

Federal tax credits

There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.

Federal housing programs

HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.

Counties

Cities